流场不均匀对液体火箭发动机纵向振荡燃烧影响及控制

针对常温推进剂发动机推力室再生冷却和撞击式喷注器结构，分析了推力室身部与喷注器对接部位的流场特性，对流场均匀性进行了实验测量。结果表明：推力室身部再生冷却通道出口压力存在约0.15 MPa周向不均匀。身部出口节流显著提高局部流速，使喷注器面氧化剂湍流度和不均匀性增加，进而改变燃烧特性。通过撞击喷注单元雾化试验，获得了18 m/s的推进剂入口边界流速。基于喷注器流场均匀性，提出控制推进剂流速，降低不均匀性，进而抑制纵向高频燃烧不稳定性的控制方法。发动机热试结果表明，采用（15±1） m/s的推进剂入口流速，控制方法抑制了纵向高频燃烧不稳定性。

Influence and control of non-uniform flow field on longitudinal combustion instability of liquid rocket engines

The vortex instability and pressure oscillation in the flow field are one of the important reasons for the high frequency longitudinal combustion instability of liquid rocket engine. Considering the regenerative cooling channel and impinging jet injectors in the thrust chamber ofnormal temperature propellant rocket engine, the flow field of the connecting part between the thrust chamber body and the injector was analyzed, and its uniformity were measured experimentally. Results showed that the circumferential non-uniform pressure at outlet of regenerative cooling channel was about 0.15 MPa. The use of throttling at the outlet of the cylindrical section of the thrust chamber can significantly increase the local fluid velocity and the turbulence and non-uniformity of the oxidant at the injector, thereby changing the combustion characteristics. The atomization test of impact injection unit was carried out, and the propellant inlet boundary velocity of 18 m/s was obtained. Based on the flow field uniformity of the injector, a control method of suppressing the longitudinal high frequency combustion instability was proposedby controlling the propellant flow rate and reducing the non-uniformity. The engine thermal test results showed that the control method suppressed the longitudinal high frequency combustion instability of the thrust chamber at the propellant inlet flow rate of (15±1) m/s.